The present invention relates to an actuator for an automatic cruising system.
Recently, there has been provided an improved automatic cruising system which controls the speed of an automobile at a constant level even though the driver releases an accelerator pedal, when the driver drives the automobile on a highway or the like. The present invention relates to an actuator in such an automatic cruising system, which receives a control signal from an electric controller (for example, having a micro computer) or from an accelerator such as an accelerator pedal, and operates a regulator for an automobile engine, e.g. a throttle valve regulator or throttle valve governor.
Generally, an automatic cruising system provided on an automobile has, for example, a fundamental construction as shown in FIG. 4.
A controller 1 generates an acceleration and/or deceleration control signals to keep the cruising speed at a constant level preset by the driver and provides the acceleration and/or deceleration control signals and other control signals for preventing a breakdown or uncontrollable driving as an electric signal to an actuator 3.
Though, hereinafter, an automobile having an accelerator pedal as an accelerator device and a throttle valve as an engine output regulator will be explained as a typical case, the actuator of the present invention, of course, can be employed in various types of vehicles including a motorcycle having an accelerator grip, an automobile provided with a fuel injection device, and the like.
In general, the controller 1 comprises a computer and peripheral units. The pedal operation is transmitted to the actuator 3 through a control cable as a mechanical signal. The actuator 3 receives input signals from the controller 1 and/or from the accelerator pedal 2, and gives an output signal to a throttle valve governor 4. The throttle valve govenor 4 is a device for governing the throttle valve in accordance with the output signal from the actuator 3, and thereby the throttle valve governor 4 selectively accelerates or decelerates the output of the engine, or keeps the output of the engine of a certain constant level.
In an automatic cruising system having the above-mentioned fundamental structure, the actuator 3 is normally subject to the control signal from the controller 1 during usual cruise conditions. However, when the driver depresses the accelerator pedal 2 to accelerate the automobile, the throttle valve governor 4 needs to be operated by the output signal from the accelerator pedal 2 rather than the signal from the controller 1. Further, when the driver releases the accelerator pedal 2, the governor 4 needs to be operated by the control signal from the controller 1 again.
The actuator 3 is required to have the above-mentioned functions and further to provide a compact body to conserve space in the automobile.
Though, hitherto, various typs of actuators have been known, in those conventional actuators, the mechanism for driving the control cable for output signal and the mechanism for driving the output control cable in accordance with the input signal from the accelerator pedal prior to the signal from the controller, i.e. an accelerator linkage mechanism, and the like are complicated. Therefore, the accelerator linkage mechanism is usually separated from the main construction of the actuator, and therefore the cable-driving devices, e.g. drums, are double necessary and the system becomes further complicated.
Accordingly, the conventional actuators do not satisfy the requirement of compact design in comparison with other functional parts or units of an automobile which are improved for space saving by various mechanical and electronic (mechatronic) means.
A main object of the present invention is to provide an actuator for an automatic cruising system which satisfies all necessary functions, and in addition, has a small body size.